When climate change forces animals to trek to cooler regions, these species will run into obstacles such as roads, cities, and farms. Now scientists at the University of Washington have mapped the most common paths that animals will likely take as they search for more hospitable habitat while avoiding highly-developed land.

This won’t be the first time in Earth’s history that species have dispersed in response to climate change. But today’s animals “will face many challenges that did not confront their ancestors,” the researchers write in Ecology Letters. More than 80 percent of the world’s land and nearly all of its rivers have been somehow altered by humans: Highways cut through prairies, dams block rivers, and previously-pristine areas are caught in the glare of city lights.

The study authors ran computer models and examined maps to figure out where 2,903 species would need to flee and what stood in their way. Then they predicted the paths of least resistance — that is, with the least human development — available to the animals.

Mass migrations will likely cross the Amazon Basin, southeastern Brazil, and the southeastern United States, including the Appalachian Mountains. But even these areas “are not necessarily pristine landscapes or even conducive to movement,” the authors write. And some animals, such as moles and shrews, may be too slow to reach their destinations. People could smooth the species’ paths by restoring patches of land along the way, the team says. — Roberta Kwok | 19 June 2013